WO2021043009A1

WO2021043009A1 - Crystalline sulfonated polyimide block copolymer proton exchange membrane, preparation method therefor, and use thereof

Info

Publication number: WO2021043009A1
Application number: PCT/CN2020/110481
Authority: WO
Inventors: 房建华; 郭晓霞; 童晶晶
Original assignee: 上海交通大学; 江苏引领者新材料有限公司
Priority date: 2019-09-05
Filing date: 2020-08-21
Publication date: 2021-03-11
Also published as: CN110628023B; JP2022545582A; US20220213282A1; CN110628023A

Abstract

A crystalline sulfonated polyimide block copolymer proton exchange membrane, a preparation method therefor, and use thereof, relating to the technical field of fuel cells. The chemical structural formula thereof is as shown in (I), in which the Ar₁ group is an aromatic group comprising a naphthyl group, the Ar₂ group is an aromatic group comprising at least one sulfonic group, x=5-100, m=1-200, and n=5-500. The preparation process is simple and is easy to achieve mass production; moreover, said proton exchange membrane has high proton conductivity and good durability, so that the power generation performance of the proton exchange membrane fuel cell is not easily affected by external humidification conditions, and still has good power generation performance under high-temperature and low-humidity conditions.

Description

Crystalline sulfonated polyimide block copolymer proton exchange membrane and preparation method and application thereof

Technical field

The invention relates to the technical field of fuel cells, in particular to a crystalline sulfonated polyimide block copolymer proton exchange membrane, and a preparation method and application thereof.

Background technique

The proton exchange membrane fuel cell (PEMFC) has the characteristics of high efficiency, cleanliness, and quietness. It has huge application prospects in the fields of electric vehicles, electronic equipment, household power stations, and aerospace. Especially the application of electric vehicles can reduce human oil The degree of dependence is of great significance to the sustainable development of mankind and the protection of the environment. The proton exchange membrane is one of the core components of the fuel cell. The power generation performance and service life of the fuel cell are closely related to the performance and stability of the proton exchange membrane. From the practical application point of view, the proton exchange membrane must meet the following requirements: 1) low cost, 2) high proton conductivity, 3) high mechanical strength and toughness, 4) low swelling rate, especially in the plane direction of the membrane, 5 ) Excellent chemical stability, especially anti-radical oxidation stability, 6) Low fuel and oxygen transmission rate, 7) High thermal stability. The trade name produced by DuPont in the United States is

The perfluorosulfonic acid membrane is the most typical type of proton exchange membrane. It has the advantages of excellent chemical stability and high proton conductivity, but its expensive price, high fuel permeability, and low Operating temperature(

The glass transition temperature of the fuel cell is only about 105℃, the working temperature of the fuel cell must be much lower than its glass transition temperature), high swelling rate (18%, 80℃, in water) and very poor water retention performance at high temperature The earth hinders its wide application in the field of fuel cells. Therefore, in the past two decades, scientists have been committed to the research and development of low-cost, excellent performance sulfonated hydrocarbon polymer proton exchange membrane instead of

However, including

The sulfonated polymer proton exchange membrane fuel cells in the sulfonated polymer proton exchange membrane fuel cells generally have the defect that their power generation performance depends heavily on external humidification conditions, that is, fuel cells can generate electricity well only under high humidification conditions. As the temperature increases, the humidity gradually decreases. At high temperatures (>100°C), the humidity becomes very low (<50%), and the power generation performance of the fuel cell often becomes very poor, or even unable to generate electricity at all. The proton conduction of the sulfonic acid group in the proton exchange membrane structure must have enough water molecules to participate in it to proceed smoothly. Therefore, those skilled in the art devote themselves to developing a proton exchange membrane with high conductivity under the conditions of high temperature and low humidity, so that the assembled fuel cell has good power generation performance.

Summary of the invention

In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the present invention is to overcome the technical problem including

Among the existing sulfonated polymer proton exchange membranes, the low conductivity of the fuel cell under the conditions of high temperature and low humidity has the disadvantage of poor power generation performance.

To achieve the above objective, the present invention provides a crystalline sulfonated polyimide block copolymer proton exchange membrane. The chemical structure of the crystalline sulfonated polyimide block copolymer is as follows:

The Ar ₁ group is an aromatic group including a naphthyl group, and the Ar ₂ group is an aromatic group including at least one sulfo group, x=5-100, m=1-200, and n=5-500.

Further, _{the naphthyl group in the Ar 1} group is the same as in the formula I

Connected into a six-membered ring to maximize the hydrolytic stability of the membrane.

Furthermore, the Ar ₂ group can increase the electron cloud density of the nitrogen atom connected to it, thereby ensuring the hydrolytic stability of the membrane.

Preferably, the Ar ₂ group has a linear configuration.

Further preferably, the Ar ₁ group is selected from:

Further preferably, the Ar ₂ group is selected from:

Another aspect of the present invention also provides a method for preparing a crystalline sulfonated polyimide block copolymer proton exchange membrane, the method comprising the following steps:

Step 1. Add Ar ₁ dianhydride monomer, aliphatic diamine monomer, and phenolic solvent into the first container, heat to 50-120°C for 1-10h, then heat to 150-200°C for 2-30h, To prepare polyimide hydrophobic block prepolymer, the reaction formula is as follows:

_{Step 2. Add Ar 2} type sulfonated diamine monomer, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), phenolic solvent and organic base into the second container, and heat to 50-120℃ for reaction After 1-10h, the temperature is raised to 150-200℃ and reacted for 2-30h to prepare the sulfonated polyimide hydrophilic block prepolymer solution. The reaction formula is as follows:

Step 3. Add the polyimide hydrophobic block prepolymer prepared in step 1 and the phenolic solvent to the second container, and heat to 150-200°C to react for 2-72 hours to prepare a crystalline sulfonated polyamide. The reaction formula of imine block copolymer is as follows:

Step 4. The crystalline sulfonated polyimide block copolymer prepared in Step 3 is made into a membrane and then proton exchange is performed to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.

Further, step 1 also includes the following steps: after the reaction system in step 1 is cooled to room temperature, an organic solvent is added to precipitate a first precipitate, and the first precipitate is suction filtered and vacuum dried to become a dry polyamide. The imine hydrophobic block prepolymer, the vacuum drying temperature is 160°C, and the time is 20h.

Further, step 3 also includes the following steps: after the reaction system in step 3 is cooled to 20-120°C, an organic solvent is added to precipitate a second precipitate, and the second precipitate is dried after suction filtration and vacuum drying. The crystalline sulfonated polyimide block copolymer, the vacuum drying temperature is 100°C, and the time is 20h.

Preferably, the above-mentioned organic solvent is one or more of methanol, ethanol, isopropanol, acetone and ethyl acetate.

Further, in step 4, the process of making the crystalline sulfonated polyimide block copolymer into a film is: dissolving the crystalline sulfonated polyimide block copolymer in a phenolic solvent, and casting on glass On the plate, dry at 90-110°C for 5-15 hours, and then peel the film from the glass plate.

Preferably, the concentration of the crystalline sulfonated polyimide block copolymer in the phenolic solvent is 0.5-25 w/v%.

Further, the proton exchange process in step 4 is: soak the membrane in an alcohol solution to remove the residual solvent, and then soak in a protic acid solution to perform proton exchange.

Further, after the proton exchange, the membrane is washed to be neutral with water, and then vacuum dried, the vacuum drying temperature is 50-150° C., and the drying is 2-30 hours.

Preferably, _{the molar ratio of Ar 1} dianhydride monomer to aliphatic diamine monomer in step 1 is greater than 1, and the molar ratio of Ar ₂ sulfonated diamine monomer to NTDA in step 2 is greater than 1.

Preferably, _{the molar ratio of Ar 1} dianhydride monomer to aliphatic diamine monomer in step 1 is less than 1, and the molar ratio of Ar ₂ sulfonated diamine monomer to NTDA in step 2 is less than 1.

Preferably, the above-mentioned phenolic solvent is one or more of m-cresol, o-cresol, p-cresol, o-chlorophenol, m-chlorophenol and p-chlorophenol.

Preferably, the organic base in step 2 reacts with the sulfonated diamine monomer, and the organic base is one or more of triethylamine, trimethylamine, pyridine, and 4-(N,N-dimethylamino)pyridine.

Preferably, a catalyst may be added in step 1 and step 4, and the catalyst is one or more of acetic acid, benzoic acid, chlorobenzoic acid, hydroxybenzoic acid, quinoline, isoquinoline, and pyridine.

Preferably, _{the total mass concentration of Ar 1} type dianhydride monomer and fatty diamine monomer in the solvent in step 1 is 5-40%.

The third aspect of the present invention provides the application of the crystalline sulfonated polyimide block copolymer proton exchange membrane in the battery.

Preferably, the battery is a fuel cell.

The present invention has the following technical effects:

(1) The present invention does not need to design and synthesize complex diamine and/or dianhydride monomers, and only uses common linear aliphatic diamines and common sulfonated diamine monomers, through block copolymerization technology. It can synthesize crystalline sulfonated polyimide block copolymer, the preparation process is simple, the reaction conditions are mild, and it is easy to realize industrial production;

(2) The sulfonated polyimide block copolymer of the present invention not only has a perfect microphase separation structure, but also its hydrophobic phase has significant crystallinity, which can induce a close and orderly hydrophilic phase. Agglomerate to form a proton conduction channel with good continuity, which is conducive to proton conduction, and reduces the swelling rate of the proton exchange membrane in the plane direction, and reduces the hydrogen and oxygen permeability coefficients of the membrane, so that the membrane has good thermal stability, Very high mechanical strength, very low swelling rate (membrane plane direction) and very high proton conductivity;

(3) The single cell assembled by the sulfonated polyimide block copolymer proton exchange membrane prepared by the present invention still has excellent power generation performance under very low relative humidity, and its power generation performance hardly depends on The external humidification condition overcomes the problem that traditional proton exchange membrane fuel cells generally have poor power generation performance under high temperature (such as 110°C) and low humidity (such as 25% humidity) conditions, or even inability to generate electricity.

In the present invention, unless otherwise specified, the terms used have the following meanings:

The term "Ar ₁ type dianhydride monomer" refers to a dianhydride monomer containing an Ar ₁ group, such as 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA).

The term "Ar ₂ type sulfonated diamine monomer" refers to a diamine monomer containing an Ar ₂ group, such as 4,4'-bis(4-aminophenoxy)biphenyl 3,3'-disulfonic acid (BAPBDS).

The term "fatty diamine monomer" refers to an aliphatic hydrocarbon having two amino groups, such as 1,12-diaminododecane (DDA).

In the following, the concept, specific structure and technical effects of the present invention will be further described with reference to the accompanying drawings, so as to fully understand the purpose, features and effects of the present invention.

Description of the drawings

Figure 1 is an infrared absorption spectrum diagram of a preferred embodiment of the present invention;

Figure 2 is an X-ray diffraction (XRD) spectrum of a preferred embodiment of the present invention;

Figure 3 is a transmission electron microscope photograph of a preferred embodiment of the present invention;

Figure 4-1 is a polarization curve of a preferred embodiment of the present invention at 80°C and different humidification conditions (relative humidity: 20, 50, 80 and 90%);

Figure 4-2 is the polarization curve of the comparative example of the present invention at 80°C and different humidification conditions (relative humidity: 20, 50, 80 and 100%);

Fig. 5 is a polarization curve of a preferred embodiment of the present invention at 110°C and different humidification conditions (relative humidity: 25, 30, 50, and 60%).

detailed description

The following are specific embodiments of the present invention to further describe the technical solutions of the present invention, but the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the protection scope of the present invention.

In the present invention, all operations involving raw materials that are easily oxidized or easily hydrolyzed are carried out under the protection of nitrogen. In addition, unless otherwise specified, the raw materials used in the present invention are all commercially available raw materials and can be used directly without further purification.

Example 1

Under the protection of nitrogen, add 2.95g of NTDA with a concentration of 11mmol, 2.004g of 1,12-diaminododecane (DDA) with a concentration of 10mmol, and 40mL of m-cresol into a fully dried 100mL three-necked flask. , 2.687g of benzoic acid with a concentration of 2.2mmol, 3.0mL of isoquinoline, mechanically stirred, stirred at room temperature for 0.5h, heated to 80 ℃ and reacted at this temperature for 4h, and then further heated to 180 ℃, and The reaction was continued at this temperature for 20 hours. After the reaction system dropped to room temperature, it was poured into 150 mL of methanol. The orange solid precipitate produced was washed repeatedly with methanol, filtered with suction, and the solid was extracted with acetone until the eluent was colorless, and dried under vacuum at 160°C for 20 hours. An anhydride-terminated polyimide prepolymer named X10.

Under the protection of nitrogen, add 0.846g of 4,4'-bis(4-aminophenoxy)biphenyl 3,3'-disulfonic acid (BAPBDS) with a concentration of 1.6mmol in a fully dried 100mL three-necked flask. ), 12.5mL of m-cresol and 0.7mL of triethylamine, mechanically stirred at room temperature, after BAPBDS is completely dissolved, then add 0.402g of NTDA with a concentration of 1.5mmol and 0.366g of benzoic acid with a concentration of 3.0mmol And 0.7mL isoquinoline. After mechanical stirring at room temperature for 1 hour, the temperature was slowly raised to 80° C. and reacted at this temperature for 4 hours, and then further warmed to 180° C., and the reaction was continued at this temperature for 20 hours.

After the reaction system dropped to room temperature, 0.459g of 0.1mmol X10 and 4mL m-cresol were added to the reaction flask. After stirring for 1 hour at room temperature, the reaction system was heated to 180°C and reacted at this temperature for 20 hours . After the reaction, it was cooled to 80°C and quickly poured into 150 mL of methanol. The resulting filamentous product precipitate was washed repeatedly with methanol and filtered with suction. The solid product was dried under vacuum at 100°C for 20 hours to obtain an average hydrophobic block. A crystalline sulfonated polyimide block copolymer X10Y15 with a length of 10 and an average hydrophilic block length of 15.

Dissolve X10Y15 in m-cresol to prepare a polymer solution with a concentration of 5w/v%. After degassing under negative pressure, it is cast on a clean glass plate and dried in a blast oven at 110°C for 5 hours. The film was peeled from the glass plate, and then immersed in hot methanol for 24 hours to fully remove the residual m-cresol solvent in the film. The membrane was transferred to a 1.0M sulfuric acid solution and soaked at room temperature for 72 hours for proton exchange. The membrane was taken out, washed with deionized water to neutrality, and dried in a vacuum oven at 120°C for 20 hours to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.

Figure 1 is the infrared absorption spectrum of the sulfonated polyimide block copolymer proton exchange membrane synthesized in Example 1. The ^{absorption peaks at 1020 and 1086 cm -1} are the symmetric and asymmetric stretching of sulfonic acid groups. At 1580 and 1520 cm ^-1 are the characteristic absorption peaks of the benzene ring skeleton C=C, at 1350 cm ^-1 are the C-N stretching vibration absorption peaks ^{of the imine ring, and at 1710 and 1670 cm -1} are the symmetry sum of the imine ring C=O. The asymmetric stretching vibration absorption peaks are the stretching vibration absorption peaks at 2847 and 2929 cm ^-1- CH ₂ , and the results of the infrared spectrum analysis are consistent with the structural characteristics of the polymer's functional groups.

Figure 2 is the X-ray diffraction spectrum of the sulfonated polyimide block copolymer proton exchange membrane synthesized in Example 1. There is a sharp diffraction peak at 2θ=5.05°, which is attributed to the aggregation of hydrophobic blocks The crystalline phase has a broad diffraction peak at 2θ=14.9°, which is attributed to the amorphous phase formed by the aggregation of hydrophilic blocks. XRD characterization results show that the sulfonated polyimide block copolymer does have significant crystallization. Phase domain.

Figure 3 is a transmission electron micrograph of the proton exchange membrane of the sulfonated polyimide block copolymer synthesized in Example 1. The black area represents the hydrophilic phase, and the white area represents the hydrophobic phase. It can be seen that the block copolymer protons The exchange membrane has a very significant microphase separation structure, the size of the hydrophilic domain is 2-4nm, and the hydrophilic phases are connected to each other to form a good proton conduction channel.

Example 2

Under the protection of nitrogen, add 2.95g of NTDA with a concentration of 11mmol, 2.004g of DDA with a concentration of 10mmol, 40mL of m-cresol, and 2.687g of benzoic acid with a concentration of 2.2mmol into a fully dried 100mL three-necked flask. , 3.0 mL of isoquinoline, mechanically stirred, and after stirring at room temperature for 0.5 h, the temperature was increased to 80° C. and reacted at this temperature for 4 h, and then further increased to 180° C., and the reaction was continued at this temperature for 20 h. After the reaction system dropped to room temperature, it was poured into 150 mL of methanol. The orange solid precipitate produced was washed repeatedly with methanol, filtered with suction, and the solid was extracted with acetone until the eluent was colorless, and dried under vacuum at 160°C for 20 hours. An anhydride-terminated polyimide prepolymer named X10.

Under the protection of nitrogen, add 1.639g of BAPBDS with a concentration of 3.1mmol, 25mL of m-cresol and 1.4mL of triethylamine to a fully dried 100mL three-necked flask, and stir mechanically at room temperature. After BAPBDS is completely dissolved, Then, 0.804 g of NTDA with a concentration of 3.0 mmol (the molar ratio between BAPBDS and NTDA is 31:30), 0.732 g of benzoic acid with a concentration of 6.0 mmol, and 0.9 mL of isoquinoline were sequentially added. After mechanical stirring at room temperature for 1 hour, the temperature was slowly raised to 80° C. and reacted at this temperature for 4 hours, and then further warmed to 180° C., and the reaction was continued at this temperature for 20 hours.

After the reaction system dropped to room temperature, 0.459g of 0.1mmol X10 and 4mL m-cresol were added to the reaction flask. After stirring for 1 hour at room temperature, the reaction system was heated to 180°C and reacted at this temperature for 20 hours . After the reaction, it was cooled to 80°C and quickly poured into 150 mL of methanol. The resulting filamentous product precipitate was washed repeatedly with methanol and filtered with suction. The solid product was dried under vacuum at 100°C for 20 hours to obtain an average hydrophobic block. A crystalline sulfonated polyimide block copolymer X10Y30 with a length of 10 and an average hydrophilic block length of 30.

Dissolve X10Y30 in m-cresol to prepare a polymer solution with a concentration of 5w/v%. After degassing under negative pressure, it is cast on a clean glass plate and dried in a blast oven at 110°C for 5 hours. The film was peeled from the glass plate, and then immersed in hot methanol for 24 hours to fully remove the residual m-cresol solvent in the film. The membrane was transferred to a 1.0M sulfuric acid solution and soaked at room temperature for 72 hours for proton exchange. The membrane was taken out, washed with deionized water to neutrality, and dried in a vacuum oven at 120°C for 20 hours to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.

Example 3

Under the protection of nitrogen, add 5.632 g of NTDA with a concentration of 21 mmol, 4.008 g of DDA with a concentration of 20 mmol (the molar ratio of NTDA to DDA is 21:20), and 40 mL of m-formaldehyde into a fully dried 100 mL three-necked flask. Phenol, 5.374g of benzoic acid with a concentration of 4.4mmol, 6.0mL of isoquinoline, mechanically stirred, stirred at room temperature for 0.5h, heated to 80℃ and reacted at this temperature for 4h, and then further heated to 180℃, and The reaction was continued for 20 h at this temperature. After the reaction system dropped to room temperature, it was poured into 150 mL of methanol. The orange solid precipitate produced was washed repeatedly with methanol, filtered with suction, and the solid was extracted with acetone until the eluent was colorless, and dried under vacuum at 160°C for 20 hours. An anhydride-terminated polyimide prepolymer named X20.

After the reaction system dropped to room temperature, 0.898g of 0.1mmol X20 and 6mL m-cresol were added to the reaction flask. After stirring for 1 hour at room temperature, the reaction system was heated to 180°C and reacted at this temperature for 20 hours . After the reaction, it was cooled to 80°C and quickly poured into 150 mL of methanol. The resulting filamentous product precipitate was washed repeatedly with methanol and filtered with suction. The solid product was dried under vacuum at 100°C for 20 hours to obtain an average hydrophobic block. A crystalline sulfonated polyimide block copolymer X20Y30 with a length of 20 and an average hydrophilic block length of 30.

Dissolve X20Y30 in m-cresol to prepare a polymer solution with a concentration of 5w/v%. After degassing under negative pressure, it is cast on a clean glass plate and dried in a blast oven at 110°C for 5 hours. The film was peeled from the glass plate, and then immersed in hot methanol for 24 hours to fully remove the residual m-cresol solvent in the film. The membrane was transferred to a 1.0M sulfuric acid solution and soaked at room temperature for 72 hours for proton exchange. The membrane was taken out, washed with deionized water to neutrality, and dried in a vacuum oven at 120°C for 20 hours to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.

Example 4

Under the protection of nitrogen, add 3.468g of 4,4'-(biphenylenedioxy)bis(1,8-naphthalene anhydride) (BPNDA), 1.002g of DDA with a concentration of 5.0mmol (the molar ratio of BPNDA to DDA is 6:5), 40mL of m-cresol, 1.344g of benzoic acid with a concentration of 1.1mmol, 1.5mL of isoquinoline, mechanical stirring, room temperature After stirring for 0.5h, the temperature was raised to 80°C and reacted at this temperature for 4h, and then the temperature was further raised to 180°C, and the reaction was continued at this temperature for 20h. After the reaction system dropped to room temperature, it was poured into 150 mL of methanol. The orange solid precipitate produced was washed repeatedly with methanol, filtered with suction, and the solid was extracted with acetone until the eluent was colorless, and dried under vacuum at 160°C for 20 hours. An anhydride-terminated polyimide prepolymer named X5.

Under the protection of nitrogen, add 1.109g of 4,4'-bis(4-aminophenoxy)biphenyl 3,3'-disulfonic acid (BAPBDS) with a concentration of 2.1mmol in a fully dried 100mL three-necked flask. ), 12.5mL of m-cresol and 0.98mL of triethylamine, mechanically stirred at room temperature, after the BAPBDS is completely dissolved, then add 0.536g of NTDA with a concentration of 2.0mmol, 0.488g of benzoic acid with a concentration of 4.0mmol And 0.53mL isoquinoline. After mechanical stirring at room temperature for 1 hour, the temperature was slowly raised to 80° C. and reacted at this temperature for 4 hours, and then further warmed to 180° C., and the reaction was continued at this temperature for 20 hours.

After the reaction system dropped to room temperature, 0.431g of 0.1mmol X5 and 4mL m-cresol were added to the reaction flask. After stirring for 1 hour at room temperature, the reaction system was heated to 180°C and reacted at this temperature for 20 hours . After the reaction, it was cooled to 80°C and quickly poured into 150 mL of methanol. The resulting filamentous product precipitate was washed repeatedly with methanol and filtered with suction. The solid product was dried under vacuum at 100°C for 20 hours to obtain an average hydrophobic block. A crystalline sulfonated polyimide block copolymer X5Y20 with a length of 5 and an average hydrophilic block length of 20.

Dissolve X5Y20 in m-cresol to prepare a polymer solution with a concentration of 5w/v%. After degassing under negative pressure, it is cast on a clean glass plate and dried in a blast oven at 110°C for 5 hours. The film was peeled from the glass plate, and then immersed in hot methanol for 24 hours to fully remove the residual m-cresol solvent in the film. The membrane was transferred to a 1.0M sulfuric acid solution and soaked at room temperature for 72 hours for proton exchange. The membrane was taken out, washed with deionized water to neutrality, and dried in a vacuum oven at 120°C for 20 hours to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.

Example 5

Under the protection of nitrogen, add 1.639g of 2,2'-bis(4-sulfophenoxy)benzidine (BSPOB) with a concentration of 3.1mmol and 20mL of m-cresol to a fully dried 100mL three-necked flask. And 1.4mL of triethylamine, mechanically stirred at room temperature, after the BSPOB is completely dissolved, add 0.804g of NTDA (the molar ratio between BSPOB and NTDA is 31:30) with a concentration of 3.0mmol, 0.732g concentration It is 6.0 mmol of benzoic acid and 0.9 mL of isoquinoline. After mechanical stirring at room temperature for 1 hour, the temperature was slowly raised to 80° C. and reacted at this temperature for 4 hours, and then further warmed to 180° C., and the reaction was continued at this temperature for 20 hours.

Comparative example 1

Under the protection of nitrogen, add 0.2004g of DDA with a concentration of 1mmol, 0.793g of BAPBDS with a concentration of 1.5mmol, 17mL of m-cresol and 0.7ml of triethylamine into a fully dried 100mL three-necked flask, and stir at room temperature until the diamine The monomer is completely dissolved. Then add 1mL isoquinoline, 0.635g NTDA with a concentration of 2.5mmol and 0.635g of benzoic acid with a concentration of 5.2mmol), stir at room temperature for 0.5h, then slowly increase the temperature to 80℃, and react at this temperature for 4h, and then the reaction The temperature rose to 180°C, and the reaction was continued at this temperature for 20 hours. The heating was stopped, and when the reaction system was cooled to 80°C, it was poured into 200 mL of methanol to obtain a filamentous precipitate. After suction filtration, the filamentous product was thoroughly washed with methanol, and then dried at 100° C. under vacuum for 10 hours.

The above-mentioned sulfonated polyimide random copolymer was dissolved in m-cresol to prepare a polymer solution with a concentration of 5w/v%. After degassing under negative pressure, it was cast on a clean glass plate and placed on 110 Dry in a blast oven at ℃ for 5h. The film was peeled from the glass plate, and then immersed in hot methanol for 24 hours to fully remove the residual m-cresol solvent in the film. The membrane was transferred to a 1.0M sulfuric acid solution and soaked at room temperature for 72 hours for proton exchange. The membrane was taken out, washed with deionized water to neutrality, and dried in a vacuum oven at 120°C for 20 hours to prepare a sulfonated polyimide random copolymer proton exchange membrane.

Ion exchange capacity and proton conductivity test:

Accurately weigh 0.2～0.3g of the dried sample film, cut it into small pieces and put it into 50mL saturated sodium chloride solution, and stir at room temperature for three days. The membrane was taken out and washed three times with a small amount of deionized water. All the washing liquid was collected and combined with the aforementioned saturated sodium chloride solution, and the mixed liquid was titrated with a sodium hydroxide solution of known concentration. Calculate the ion exchange capacity (IEC) according to the following formula: IEC=C _NaOH ·V _NaOH /m, where C _NaOH is the concentration of the NaOH solution, V _NaOH is the volume of NaOH consumed in the titration, and m is the weight of the polymer membrane quality. The crystalline sulfonated polyimide block copolymer proton exchange membrane prepared in Examples 1-5 and the amorphous sulfonated polyimide prepared in Comparative Example 1 were measured on the Hioki3553Hitester AC impedance instrument by the AC impedance method. The proton conductivity of the amine random copolymer proton exchange membrane and the Nafion212 proton exchange membrane of DuPont Company in the United States were measured. The test frequency range: 42Hz-5MHz; the test medium: ultrapure water; the test temperature: 40 or 80 ℃. The proton conductivity σ (unit: S/cm) is calculated according to the following formula: σ=D/(LBR), where D is the distance between the two electrodes (5mm), L is the width of the membrane sample (5mm), B is the thickness of the film sample (30-50 μm), and R is the measured impedance of the sample.

The test results of ion exchange capacity and proton conductivity are shown in Table 1. The ion exchange membranes of Example 1-5 sulfonated polyimide block copolymer membrane and Comparative Example 1 sulfonated polyimide random copolymer membrane The capacity is similar, but the ion exchange membrane capacity of the sulfonated polyimide block copolymer membrane of Example 1-5 is significantly higher than that of Nafion212. and,

The proton conductivity of the sulfonated polyimide block copolymer membrane of Examples 1-5 at 40°C and 80°C was significantly higher than that of the sulfonated polyimide random copolymer membrane of Comparative Example 1 and Nafion212.

Table 1: Test results of ion exchange capacity and proton conductivity

Power generation performance test:

Using 40% Pt/C (Johnson Matthey Company) as the electrode catalyst, Nafion as the binder, the catalyst ink is prepared, and then sprayed on both sides of the proton exchange membrane, each with an effective area of 5 cm ² , and the anode and cathode are supported by platinum catalysts. The amount is 0.5 mg/cm ² . The fuel cell test equipment (Scribner, 850e, U.S.) was used to test the power generation performance of the fuel cell single cells assembled by implementation cases 1-5, comparative example 1, and Nafion212. The test conditions for the power generation performance of all single cells are as follows: anode gas (hydrogen) and cathode gas (oxygen) flow rates are: 200mL/min, temperature: 95℃, back pressure: 150KPa, anode and cathode gas humidification conditions are the same, and relative The humidity is controlled to 50% respectively.

The test results are shown in Table 2. The single cell assembled by the sulfonated polyimide block copolymer proton exchange membrane prepared in Examples 1-5 and the sulfonated polyimide prepared in Comparative Example 1 were randomly copolymerized. Compared with the material film, the open circuit voltage of Examples 1-5 is slightly higher than that of Comparative Example 1, but the peak power density of Examples 1-5 is much higher than that of Comparative Example 1 (the highest is about 1.6 times). Compared with the single cell assembled by Nafion212, the single cell assembled by the sulfonated polyimide block copolymer proton exchange membrane prepared in Examples 1-5 not only has higher open circuit voltage than Nafion212, but also implemented The peak power density of Examples 1-5 is much higher than Nafion212 (the highest is about 1.5 times). This indicates that the single cell assembled with the proton exchange membrane of the sulfonated polyimide block copolymer prepared in Examples 1-5 has more excellent power generation performance.

Table 2: Power generation performance test results

质子交换膜Proton exchange membrane	膜厚(μm)Film thickness (μm)	开路电压(V)Open circuit voltage (V)	峰值功率密度(mW/cm ²) Peak power density (mW/cm ² )
实施例1Example 1	3030	1.021.02	939939
实施例2Example 2	3131	1.041.04	945945
实施例3Example 3	3030	1.021.02	875875
实施例4Example 4	3232	1.031.03	901901
实施例5Example 5	3131	1.061.06	10241024
比较例1Comparative example 1	3030	1.011.01	636636
Nafion212Nafion212	5555	0.970.97	682682

As shown in Figure 4-1 and Figure 4-2, at 80°C, the power generation performance of the single cell assembled by the sulfonated polyimide block copolymer proton exchange membrane is almost independent of the humidification conditions, even at a very low relative temperature. Under humidity (20%), the batteries all show high power generation performance (peak power density: 990mW/cm ² ); while the power generation performance of single cells assembled with sulfonated polyimide random copolymer proton exchange membrane is generally poor , And is closely related to humidification conditions. With the decrease of relative humidity, the power generation performance of the battery further deteriorates. The peak power density of the battery is only 290mW/cm ² at a very low relative humidity (20%).

As shown in Figure 5, the temperature has little effect on the power generation performance of the single cell assembled with the sulfonated polyimide block copolymer proton exchange membrane. Even if the temperature is increased to 110°C, the battery still shows high power generation. Performance (peak power density: 807mW/cm ² ), and power generation performance is almost independent of humidification conditions.

The preferred embodiments of the present invention have been described in detail above. It should be understood that ordinary technologies in the field can make many modifications and changes according to the concept of the present invention without creative labor. Therefore, all technical solutions that can be obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

A crystalline sulfonated polyimide block copolymer proton exchange membrane is characterized in that the chemical structural formula of the crystalline sulfonated polyimide block copolymer is as follows:

The Ar 1 group is an aromatic group including a naphthyl group, and the Ar 2 group is an aromatic group including at least one sulfo group, x=5-100, m=1-200, and n=5-500.
The proton exchange membrane of claim 1, wherein the naphthyl group in the Ar 1 group is the same as that in formula I
Connected into a six-membered ring.
The proton exchange membrane according to claim 1 or 2, wherein the Ar 2 group can increase the electron cloud density of the nitrogen atom connected to it.
The proton exchange membrane according to any one of claims 1 to 3, wherein the Ar 1 group is selected from:
The proton exchange membrane according to any one of claims 1 to 4, wherein the Ar 2 group is selected from:
A method for preparing a crystalline sulfonated polyimide block copolymer proton exchange membrane according to any one of claims 1 to 5, wherein the method comprises the following steps:

Step 1. Add Ar 1 dianhydride monomer, aliphatic diamine monomer, and phenolic solvent into the first container, heat to 50-120°C for 1-10h, then heat to 150-200°C for 2-30h, To prepare polyimide hydrophobic block prepolymer;

Step 2. Add Ar 2 type sulfonated diamine monomer, 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA), phenolic solvent and organic base into the second container, and heat to 50-120℃ for reaction After 1-10h, heat up to 150-200℃ and react for 2-30h to prepare sulfonated polyimide hydrophilic block prepolymer solution;

Step 3. Add the polyimide hydrophobic block prepolymer and phenolic solvent prepared in step 1 to the second container, and heat up to 150-200°C to react for 2-72 hours to prepare crystalline sulfonate Modified polyimide block copolymer;

Step 4. The crystalline sulfonated polyimide block copolymer prepared in Step 3 is made into a membrane and then proton exchange is performed to prepare a crystalline sulfonated polyimide block copolymer proton exchange membrane.
The preparation method according to claim 6, wherein step 1 further comprises the following step: after the reaction system in step 1 is cooled to room temperature, an organic solvent is added to precipitate the first precipitate, and the first precipitate is pumped After filtration and vacuum drying, it is the dried polyimide hydrophobic block prepolymer.
The preparation method according to claim 6, characterized in that, step 3 further comprises the following steps: after the temperature of the reaction system in step 3 is cooled to 20-120°C, an organic solvent is added to precipitate a second precipitate, and the second precipitate After suction filtration and vacuum drying, it is a dry crystalline sulfonated polyimide block copolymer.
The preparation method according to claim 6, wherein the process of forming the crystalline sulfonated polyimide block copolymer into a film in step 4 is: inserting the crystalline sulfonated polyimide into a film The segment copolymer is dissolved in a phenolic solvent, poured on a glass plate, dried at 90-110°C for 5-15 hours, and then the film is peeled from the glass plate.
7. The preparation method according to claim 6, wherein the proton exchange process in step 4 is: soaking the membrane in an alcohol solution to remove residual solvent, and then soaking in a protic acid solution for proton exchange.
The preparation method according to claim 7 or 8, wherein the organic solvent is one or more of methanol, ethanol, isopropanol, acetone and ethyl acetate.
The preparation method according to claim 6, wherein the phenolic solvent is one or more of m-cresol, o-cresol, p-cresol, o-chlorophenol, m-chlorophenol and p-chlorophenol .
The preparation method according to claim 6, wherein the organic base in step 2 is one or more of triethylamine, trimethylamine, pyridine and 4-(N,N-dimethylamino)pyridine .
The preparation method according to claim 6, wherein a catalyst can be added in step 1 and step 4, and the catalyst is acetic acid, benzoic acid, chlorobenzoic acid, hydroxybenzoic acid, quinoline, isoquinoline And one or more of pyridine.
The application of the crystalline sulfonated polyimide block copolymer proton exchange membrane according to any one of claims 1 to 5 in a battery.
The application according to claim 15, wherein the battery is a fuel cell.